If my boyfriend went down on me after we made out and i had a cold sore that was starting up, could he have given me herpes? i did wash 10hours after

No risk, no worry: People are immune (at least highly resistant) to new infections with the same type of HSV (HSV1 or 2) they already have. They are especially unlikely to get infected in a new body area with their own virus. You can't get a genital infection with the HSV1 causing your own cold sores. The main thing is that you avoid kissing or performing oral sex on bf when you have a cold sore.